2. STOCK-BASED COMPENSATION (Details 2) - Stock Option and RSU Transactions - shares	3 Months Ended				9 Months Ended
	Feb. 28, 2018	Nov. 30, 2017	Aug. 31, 2017	Feb. 28, 2017	Feb. 28, 2018	Feb. 28, 2017
Available Shares, Beginning (in thousands)	1,840	1,881	2,169		2,169
Options granted (in thousands)	(19)	(41)	(224)
RSUs granted (in thousands)	0	0	(64)	0	(64)	(157)
Shares cancelled (in thousands)	13
Plan shares expired (in thousands)	(2)
Available Shares, Ending (in thousands)	2,169	1,840	1,881		2,169